Calibre opens in about a second. The program resides on an SSD, but my library is on a WD hard drive that clunks and groans as if it was in its death throes. I do have Calibre set up as a trusted application, though. Doing the unmentionable (thanks, Alf) and converting to other formats works in a flash.

I will admit that Calibre was fairly slow on my nine-year-old computer that wasn't exactly cutting edge when I got it, but I never imagined that to be a problem with Kaspersky (or Calibre.)